1. Field of the Invention
The present invention relates to radio communication systems, and more particularly, to an apparatus and a method of transmitting hierarchically modulated signals in radio communication systems.
2. Related Art
Non-uniform constellation of a digital video broadcasting-terrestrial (DVB-T) standard is not used in actual broadcasting environments due to the efficiency and performance thereof. Meanwhile, a DVB-T2 standard, a second-generation terrestrial. TV standard in Europe that is not compatible with the existing DVB-T standard does not adopt a hierarchical modulation technology. As compared with the existing DVB-T, various transmission technologies have been adopted in order to improve transmission efficiency and receive performance.
A need exists for a method of improving transmission efficiency while maintaining compatibility with the existing transmission system such as DVB-T, digital video broadcasting—satellite 2nd generation (DVB-S2), or advanced terrestrial-digital multimedia broadcasting (AT-DME)